Category: Applications

AERO is essentially the satellite based version of aircraft ACARS. AERO's L-band signals contains short ground to air messages with things like weather reports and flight plans. The C-band signals are the air to ground portion of AERO and more difficult to receive as they require an LNB and large dish. However they are much more interesting as they contain flight position data, like ADS-B.

Over on YouTube Tomasz Haddad has uploaded a video of C-band AERO being received from the Inmarsat 3 F2 (Atlantic Ocean Region – East (AOR-E) 15W satellite. He uses a 1.80m motorized satellite dish with Kaonsat KS-N201G C-band LNB, a Prof 7301 PCI satellite card (to power the LNB) and an RTL-SDR V3. The C-band LNB translates the high C-band frequencies down to L-band which is receivable with an RTL-SDR. He notes that the LNB drifts quite a lot as it is not frequency stabilized.

With the signals received by his setup he's able to use the JAERO decoding software together with Virtual Radar Server to plot aircraft positional data using Virtual Radar Server. The plotted aircraft are mostly all in the middle of the ocean or in remote areas, which is where C-band AERO is normally used due to the lack of ground ADS-B stations.

A linear transponder is essentially a repeater that works on a range of frequencies instead of a fixed frequency. For example, a normal repeater may receive at 145 MHz, and repeat the signal at 435 MHz. However, a linear transponder would receive a wider bandwidth, and add a set frequency offset to the received signal. For example a signal received by a linear transponder that receives from 145 - 145.5 MHz, may receive a signal at 145.2 MHz and it would translate that up to 435.2 MHz. Another signal received at 145.4 MHz would translate up to 435.4 MHz. Hence the received frequency linearly translates to the transmitted frequency.

In the new version the 'Net Info' button is now functioning and it is possible to see the current calls, groups, and meta information on the current cell and neighbour cell. It also appears that it has been updated to allow for multiple SDR# TETRA decoder instances to be opened simultaneously now for wider band monitoring.

Over on YouTube the web show Hacker Warehouse have created a video explaining wireless pagers and how RTL-SDRs can be used to sniff them. In the video host Troy Brown starts by explaining what pagers are and how they work, and then he shows how to decode them with SDR# and PDW. We have a tutorial on this project available here too.

Later in the video he shows some examples of pager messages that he's received. He shows censored messages such as hospital patient data being transmitted in plain text, sports scores, a memo from a .gov address claiming allegations of abuse from a client, office gossip about a hookup, a message about a drunk man with a knife, a message from a Windows server with IP address and URL, a message from a computer database, and messages from banks.

In the past we've also seen an art installation in New York which used SDR to highlight the blatant breach of privacy that these pager messages can contain.

Over on Twitter and his github.io page, Pieter Noordhuis (@pnoordhuis) has shared details about his low cost RTL-SDR based GOES satellite receiving setup. GOES 15/16/17 are geosynchronous weather satellites that beam back high resolution weather images and data. In particular they send beautiful high resolution 'full disk' images which show one side of the entire earth. As the satellites are in geosynchronous orbit, they are quite a bit further away from the earth. So compared to the more easily receivable low earth orbit satellites such as the NOAA APT and Meteor M2 LRPT satellites, a dish antenna, good LNA and possibly a filter is required to receive them. However fortunately, as they are in a geosynchronous orbit, the satellite is in the same position in the sky all the time, so no tracking hardware is required.

In the past we've seen people receive these images with higher end SDRs like the Airspy and SDRplay. However, Pieter has shown that it is possible to receive these images on a budget. He uses an RTL-SDR, a 1.9 GHz grid dish antenna from L-Com, a Raspberry Pi 2, the NooElec 'SAWBird' LNA, and an additional SPF5189Z based LNA. The SAWBird is a yet to be released product from NooElec. It is similar to their 1.5 GHz Inmarsat LNA, but with a different SAW filter designed for 1.7 GHz GOES satellites. The total cost of all required parts should be less than US $200 (excluding any shipping costs).

Pieter also notes that he uses the stock 1.9 GHz feed on the L-com antenna, and that it appears to work fine for the 1.7 GHz GOES satellite frequency. With this dish he is able to receive all three GOES satellites at his location with the lowest being at 25 degrees elevation. If the elevation is lower at your location he mentions that a larger dish may be required. It may be possible to extend the 1.9 GHz L-Band dish for better reception with panels from a second cheaper 2.4 GHz grid dish, and this is what @scott23192 did in his setup.

For software Pieter uses the open source goestools software that Pieter himself developed. The software is capable of running on the Raspberry Pi 2 and demodulating and decoding the signal, and then fully assembling the decoded signal into files and images.

The NT1065 is an all-in-one 4-channel global navigation satellite system (GNSS) receiver chip. It is highly versatile and can receive and decode multiple navigation satellites such as GPS, GLONASS, Galileo, BeiDou, IRNSS and QZSS. Being able to receive so many satellites, it is capable of centimeter level positioning.

The team at Amungo Navigation have taken this chip and have created a product called the NUT4NT+ which is essentially a development board for the NT1065, and all the software for signal processing with it is provided as open source software. In the near future they are planning to begin fundraising for the product over on the crowd funding site CrowdSupply.

One very interesting application that they have been developing with a device similar to the NUT5NT+ is a GPS Jammer/Spoofer detector system which they call the Amungo XNZR. This is a combined 4-channel GNSS receiver and 4-antenna GNSS antenna system built into a small package that fits onto the back of an Android tablet. When connected to the software it uses augmented reality (AR) to show you exactly where GPS jammers are in the vicinity by using coherent signal processing. If you're not familiar with AR, this is the technique of overlaying digital data/images on top of a live real world camera view.

Detecting a Kremlin GPS Spoofer in Augmented Reality

In the video below they take their XNZR detector to Varvarka Street in Moscow Russia and determine the location of a GPS spoofer in the vicinity.

More information about their product can be found on their homepage, and on various interesting forum posts by someone from the company that detail some of their experiments. Note that the forum posts are in Russian, but Google Translate can be used to translate the text.

Over on YouTube Debashish Sahu has uploaded a video showing how he uses an RTL-SDR to capture and decode consumption data from his home electric/gas/water utility meters. He uses the rtl_amr software which already supports a wide range of meters such as Debashish's gas meter. Later in the video he shows a Python script that he's written which continuously grabs the data from rtl_amr, and passes it into the Home Assistant software using JSON. Then in Home Assistant the data is graphed, and he is able to determine points of interest, such as when appliances turned on or off.

The Freqshow software is an RTL-SDR compatible tool for Raspberry Pi devices that can render live spectrum and waterfall displays. It is designed to run on portable touchscreens that plug into the Raspberry Pi. We've posted about freqshow a few times in the past.

The additional features are many. Additional features include: Full resolution zooming, I and Q Swap, 9 different pre FFT windowing functions to choose from. Center frequency offset or shift. PPM correction for the RTL2832. FFT averaging or FFT peaking. Easy frequency up and down from main screen. Easy Scale adjustment from main screen.

On YouTube he's also posted a video that demonstrates the software in action when running on an Adafruit 2.8" and Pi Foundation 7" TFT capacitive touch screen. Dan uses the software as a panadapter for his ham radio.

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What is RTL-SDR

The RTL-SDR is an ultra cheap software defined radio based on DVB-T TV tuners with RTL2832U chips. The RTL-SDR can be used as a wide band radio scanner. It may interest ham radio enthusiasts, hardware hackers, tinkerers and anyone interested in RF.